Supercapacitor-emulating fast-charging batteries and devices

ABSTRACT

Methods and supercapacitor-emulating fast-charging batteries are provided. Methods comprise configuring a fast-charging battery to emulate a supercapacitor with given specifications by operating the fast-charging battery only within a partial operation range which is defined according to the given specifications of the supercapacitor and is smaller than 20%, possibly 5% or 1%, of a full operation range of the fast-charging battery. Devices are provided, which comprise control circuitry and a modified fast-charging lithium ion battery having Si, Ge and/or Sn-based anode active material and designed to operate at 5 C at least and within a range of 5% at most around a working point of between 60-80% lithiation of the Si, Ge and/or Sn-based anode active material, wherein the control circuitry is configured to maintain a state of charge (SOC) of the battery within the operation range around the working point.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/434,432, filed Dec. 15, 2016, which is incorporated by reference inits entirety.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates to the field of energy storage devices,and more particularly, to an emulation of supercapacitors usingfast-charging batteries.

2. Discussion of Related Art

Supercapacitors, also known as ultracapacitors, are capacitors with highcapacitance which are used to provide electric energy bursts, i.e.,short term high energy pulses. In these applications, supercapacitorsare superior to batteries in their ability to deliver much more chargeover a shorter time and in their ability to undergo many more chargingand discharging cycles. The superior performance in these respects isdue to the fact that the operation of supercapacitors is based onelectrostatic energy storage while the operation of batteries is basedon electrochemical redox reactions, which are generally slower and causemore electrode degradation over time. Supercapacitors are designed invarious ways, such as double layer supercapacitors (e.g., electricdouble-layer capacitors (EDLC)), pseudocapacitors, hybrid capacitorsetc.

There is a direct relation between the supercapacitor's physical size tothe charge it can store and the energy it can deliver. Typicalsupercapacitors range from 0.001 Wh of stored energy for dimensions inthe scale (order of magnitude) of 1 cm, weight of 1 gr and maximalcurrent of 0.5-1 A (rated capacitance 1 F) to 4 Wh of stored energy fordimensions in the scale (order of magnitude) of 10 cm, weight of 500 grand maximal current reaching 2000 A with continuous currents reaching200 A (rated capacitance 3000 F). Larger supercapacitors are made ofmultiple supercapacitor units to store and deliver larger energyratings.

SUMMARY OF THE INVENTION

The following is a simplified summary providing an initial understandingof the invention. The summary does not necessarily identify key elementsnor limit the scope of the invention, but merely serves as anintroduction to the following description.

One aspect of the present invention provides a device comprising controlcircuitry and a modified fast-charging lithium ion battery having Si, Geand/or Sn-based anode active material and designed to operate at 5 C atleast and within an operation range of 5% at most around a working pointof between 60-80% lithiation of the Si, Ge and/or Sn-based anode activematerial, wherein the control circuitry is configured to maintain astate of charge (SOC) of the battery within the operation range aroundthe working point.

These, additional, and/or other aspects and/or advantages of the presentinvention are set forth in the detailed description which follows;possibly inferable from the detailed description; and/or learnable bypractice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of embodiments of the invention and to showhow the same may be carried into effect, reference will now be made,purely by way of example, to the accompanying drawings in which likenumerals designate corresponding elements or sections throughout.

In the accompanying drawings:

FIG. 1 is a high level schematic illustration of a device which emulatesa supercapacitor using a modified fast-charging battery, according tosome embodiments of the invention.

FIG. 2 is a high level schematic illustration ofsupercapacitor-emulating fast-charging battery and its configuration,according to some embodiments of the invention.

FIG. 3 is a high level schematic flowchart illustrating a method ofemulating a supercapacitor by a fast-charging battery, according to someembodiments of the invention.

FIG. 4A is a high level schematic illustration of various anodeconfigurations, according to some embodiments of the invention.

FIG. 4B is a high level schematic illustration of partial lithiation andmechanical barriers for lithiation of the anode material particles,according to some embodiments of the invention.

FIGS. 5A-5C are high level schematic illustrations relating to theselection of working point and narrow operation range, according to someembodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, various aspects of the present inventionare described. For purposes of explanation, specific configurations anddetails are set forth in order to provide a thorough understanding ofthe present invention. However, it will also be apparent to one skilledin the art that the present invention may be practiced without thespecific details presented herein. Furthermore, well known features mayhave been omitted or simplified in order not to obscure the presentinvention. With specific reference to the drawings, it is stressed thatthe particulars shown are by way of example and for purposes ofillustrative discussion of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

Before at least one embodiment of the invention is explained in detail,it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention is applicable to other embodiments that may bepracticed or carried out in various ways as well as to combinations ofthe disclosed embodiments. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Methods and supercapacitor-emulating fast-charging batteries areprovided. Methods comprise configuring a fast-charging battery toemulate a supercapacitor with given specifications by operating thefast-charging battery only within a partial operation range which isdefined according to the given specifications of the supercapacitor andis smaller than 20%, possibly 5% or 1%, of a full operation range of thefast-charging battery. The full operation range may be defined as any of(i) 0-100% state of charge (SOC) of the battery, (ii) potential 0-100%state of charge (SOC) of the anode material from which the battery isprepared (in case there are mechanical structures that limit thelithiation of the anode active material, as discussed below), (iii) thenominal capacity of the battery, and/or equivalent definitions. Devicesare provided, which comprise control circuitry and a modifiedfast-charging lithium ion battery having Si, Ge and/or Sn-based anodeactive material and designed to operate at 5 C at least and within arange of 5% at most around a working point of between 60-80% lithiationof the Si, Ge and/or Sn-based anode active material, wherein the controlcircuitry is configured to maintain the SOC of the battery within theoperation range around the working point.

FIG. 1 is a high level schematic illustration of a device 100 whichemulates a supercapacitor 90 using a modified fast-charging battery100A, according to some embodiments of the invention. Device 100 maycomprise modified fast-charging battery 100A configured to enable fastcharging as explained below, and to operate within a narrow operationrange 105 around a working point 115 as configured in configurationstages 210 disclosed below. Modified fast-charging battery 100A may beoptimized to operate as part of device 100 and with respect to narrowoperation range 105 and working point 115, as disclosed below.

Device 100 may further comprise a control unit 106 configured to operatemodified fast-charging battery 100A within narrow operation range 105around working point 115 to provide an output 95 which is equivalent tothe output expected from corresponding supercapacitor 90 and/oraccording to given supercapacitor specifications 94, e.g., with respectto performance (e.g., currents, cycle life, capacity, etc.) anddimensions (e.g., size, weight) of corresponding supercapacitor 90.Device 100 may be designed to emulate any given supercapacitor 90 and/orany given supercapacitor specifications 94, as explained below.Different configurations of device 100 may be used to emulatecorresponding different supercapacitors 90.

Control unit 106 may comprise various electronic components (e.g.,diodes, switches, transistors, etc.) as circuit elements configured todetermine working point 115 and prevent charging and/or dischargingmodified fast-charging battery 100A outside a specified voltage rangecorresponding to operating range 105. For example, control circuitry 106may comprise circuit elements (e.g., diodes, switches, transistors,etc.) configured to prevent a charging current from reaching modifiedfast-charging battery 100A except in operation range 105 around workingpoint 115.

Control circuit 106 may be configured to operate modified fast-chargingbattery 100A at narrow operation range 105 around working point 115,according to configuration parameters 230 such as thecharging/discharging rate, dimension and other performance parameters offast charging battery 100A determined with respect to the emulatedsupercapacitor 94, as disclosed below. In certain embodiments, thecharging/discharging rate may be adjusted by selecting the working pointat a specific SOC with respect to a given C-rate of the battery.

It is emphasized that the disclosed invention enables configuration ofappropriate modified fast-charging battery 100A and/or device 100 forany given supercapacitor specifications, by configuring the dimensionsof modified fast-charging battery 100A and the performance of modifiedfast-charging battery 100A and/or device 100 correspondingly.

The inventors have found that for any given supercapacitorspecifications, corresponding modified fast-charging battery 100A and/ordevice 100 may indeed be designed to emulate the given supercapacitor.Examples for given supercapacitor specifications include, e.g., any of:(i) rated capacitance 1 F, stored energy 0.001 Wh, volume of ca. 1 cm³,weight of 1 gr and maximal continuous current of 0.5-1 A (depending onconditions); (ii) rated capacitance 10 F, stored energy 0.01 Wh, volumeof 3 cm², weight of 3-4 gr and maximal continuous current of 2-4 A(depending on conditions); (iii) rated capacitance 100 F, stored energy0.1 Wh, volume of ca. 10 cm³, weight of 20-25 gr and maximal continuouscurrent of 5-15 A (depending on conditions); (iv) rated capacitance300-600 F, stored energy 0.3-0.8 Wh, volume of ca. 20-30 cm³, weight of50-150 gr and maximal continuous current of 20-90 A (depending onconditions); (v) rated capacitance 1500 F, stored energy 1.5 Wh, volumeof ca. 50-60 cm³, weight of ca. 300 gr and maximal continuous current of80-150 A (depending on conditions); (vi) rated capacitance 3000-4000 F,stored energy 3-4 Wh, volume of ca. 100 cm³, weight of cal 500 gr andmaximal continuous current of 130-200 A (depending on conditions); aswell as larger supercapacitors and packs of supercapacitors, which maybe emulated by modified fast-charging batteries 100A and/or devices 100,and/or packs thereof. The inventors have found that modifiedfast-charging battery 100A and/or device 100 may be configured toreplace any of the examples of supercapacitors listed above, and provideequivalent or even superior performance with respect to the givensupercapacitor specifications.

It is noted that modified fast-charging battery 100A and/or device 100may be used in a variety of applications where a supercapacitor is used,to replace the supercapacitor by equivalent modified fast-chargingbattery 100A and/or device 100 with respect to performance,specifications and physical dimensions. For example, modifiedfast-charging battery 100A and/or device 100 may be configured toemulate large supercapacitors (see examples above) and be integrated assuch into an electrical power grid (alone or in an array of suchdevices) to smoothen out spikes in energy demand. In another example,modified fast-charging battery 100A and/or device 100 may be configuredto emulate small supercapacitors (see examples above) and be included inconsumer electronic devices to ensure an even power supply for thedevice. In certain embodiments, modified fast-charging battery 100Aand/or device 100 may be particularly advantageous with respect to theemulated supercapacitors in use cases which requires many shortoperation cycles, such as wireless sensors. As supercapacitors typicallyhave a low energy density and high leakage currents, such scenariostypically exhaust supercapacitors quickly, while the much larger energydensity and low leakage currents characterizing modified fast-chargingbattery 100A and/or device 100 may enable a much more extended operationof devices in such use cases.

FIG. 2 is a high level schematic illustration ofsupercapacitor-emulating fast-charging battery 100A and itsconfiguration, according to some embodiments of the invention. FIG. 3 isa high level schematic flowchart illustrating a method 200 of emulatinga supercapacitor by a fast-charging battery, according to someembodiments of the invention. The method stages may be carried out withrespect to battery 100. Method 200 may comprise stages for producing,preparing and/or using battery 100, irrespective of their order. FIGS.5A-5C are high level schematic illustrations relating to the selectionof working point 115 and narrow operation range 105, according to someembodiments of the invention. FIGS. 5A, 5B illustrate schematicallycharging and discharging graphs, respectively and FIG. 5C illustrates anexample for an optimal working window for selecting working point 115,as explained below.

As illustrated schematically in FIG. 2, supercapacitors 90 arecharacterized by fast-charging rates typically having a charging timerange of 2-20 sec (for the range of supercapacitors 90 presented in theBackground of the Invention), full discharge in operation, highdelivered currents (up to hundreds of amperes of continuous current persingle supercapacitor unit) and operability over a large number ofcycles (10⁵-10⁶ cycles). However, supercapacitors 90 typically sufferfrom relatively high self-discharge rates (leakage currents of about1-3% of the maximal continuous current). Moreover, while the powerdensity of supercapacitors 90 may be higher than the power density oflithium ion batteries, the energy density of lithium ion batteries issignificantly larger (typically by several orders of magnitude) than theenergy density of supercapacitors 90.

Charge and discharge rate are conventionally measured with respect tobattery capacity. Thus, a charging rate of 1C means that a battery willreach nominal capacity in one hour of charging. Likewise, a 1 Cdischarge rate means that a battery will deplete fully in 1 hour. Asused herein, “fast charge” refers to a charging rate of 5 C or greater.

Advantageously, fast-charging batteries (e.g., batteries configured tooperate at a charge rate of at least about 5 C, and in embodiments at arate of about 15 C to about 50 C and a discharge rate in embodiments ofabout 5 C) have low self-discharge rates (e.g., about 10% of the leakagecurrent of a comparable supercapacitor), higher working potentials,shorter charging times and higher energy densities, which provide asignificant advantage over supercapacitors 90. Fast charging lithium ionbatteries that may be configured to emulate a supercapacitor accordingto the invention may be of any construction now known or hereafterdeveloped, including those with metalloid-based anodes, as described inU.S. Pat. No. 9,472,804, which is incorporated by reference.

However, prior art fast-charging batteries typically provide lowercurrents (typically 1-10% of the continuous currents provided by acomparable supercapacitor) and operate for a smaller number of cycles(typically 10³ cycles) compared to supercapacitors 90, which typicallyprovide higher currents and operate for a larger number of cycles(typically 10⁵-10⁶ cycles).

Surprisingly, the inventors have figured out a way to emulatesupercapacitors 90 by fast-charging batteries 100, thereby retaining theintrinsic advantages of fast-charging batteries while overcoming theprior art limitations and drawbacks of fast-charging batteries comparedto supercapacitors 90.

Method 200 comprises configuring devices 100 and/or modifiedfast-charging battery 100A to emulate supercapacitor 90 with givenspecifications by operating the fast-charging battery only within anarrow partial operation range 105 around working point 115, which isdefined according to the given specifications of supercapacitor 90 andis smaller than 20% of the full operation range of the fast-chargingbattery (see above). Partial operation range 105 may be determinedaccording to the required performance and may be 20%, 10%, 5%, 1% or anyother partial range of the full operation range of the lithium ionbattery.

In certain embodiments, fast-charging battery 100A may be modified to becharged and discharged only over narrow operation range 105 aroundworking point 115 or over a range including narrow operation range 105,but not over the full operation range of an unmodified fast-chargingbattery. For example, modified battery 100A may be designed to allowonly small ranges of expansion of anode material particles 110 (seeFIGS. 4A and 4B below and subsequent disclosure) and therefore not beoperable as a regular lithium ion battery over a wide range of chargingstates.

Method 200 may be used to provide devices 100 and/or modifiedfast-charging batteries 100A which emulate a wide range ofsupercapacitors 90, at a corresponding wide range of operationspecifications. Fast-charging batteries 100A may be configured toemulate corresponding supercapacitors 90 with respect to differentperformance requirements, such as a same continuous current requirement,a same weight requirement, a same dimensions requirement and so forth,adjusting the unrestricted parameters of fast-charging battery 100A toemulate specific supercapacitor 90 using only partial operation range105 of fast-charging battery 100A to equal the performance of specificsupercapacitor 90. In certain embodiments, fast-charging batteries 100Amay be configured to emulate supercapacitors 90 within a performanceenvelope defined by the given specifications, possibly without havingany specific identical parameters (such as current or dimension). Theperformance envelope may be defined in terms of one or more of theparameters listed below and/or in terms of any combination thereof.Embodiments of modifications of fast-charging batteries 100A andconfigurations of devices 100 and control circuitry 106 are disclosedbelow (see e.g., FIG. 4B).

Without being bound by theory, the inventors suggest that operatingmodified fast-charging batteries 100A over a partial operation range 105enables larger continuous currents to be provided because only a smallportion of the whole charging or discharging curve is utilized (seeschematic illustration of a charging curve in FIG. 2) and increases thenumber of cycles as in each cycle different areas of battery 100A areactually operative (see schematic illustration by the checkering ofbattery 100A in FIG. 2) and therefore battery 100A in the disclosedoperation mode can sustain a number of cycles which is, e.g., two tothree orders of magnitudes larger than a typical battery operated overits full range—thereby bridging the gap to supercapacitors 90.

The following notation and units are used to denote the parameters ofsupercapacitors 90 (using the subscript SC for “supercapacitor”, e.g.,E_(SC)) and fast-charging batteries 100A (using the subscript FCB, e.g.,Ep_(FCB)).

Energy parameters: The stored energy is denoted by E (Wh), andgravimetric and volumetric energy densities are denoted by E_(g) (Wh/kg)and E_(v) (Wh/l), respectively. The power density is denoted by P(W/kg).

Physical dimensions: The typical dimensions are characterized herein, ina non-limiting manner, by the unit's volume denoted by d (cm³) and theweight is denoted by w (gr).

Performance parameters: The rated voltage is denoted by V (V), themaximal continuous current is denoted by I (A) and the charging time isdenoted by t (1/C rate, e.g., for 50 C, t= 1/50 in hours).

Operation parameter: Partial operation range 105 in which fast-chargingbattery 100A is operated to emulate a given supercapacitor 90 is denotedby SOC (state of charge, %), e.g., in case fast-charging battery 100A isoperated only at 2% of the total charging/discharging range offast-charging battery 100A, then SOC=2% (see examples below).

Equations 1 present the relations between these parameters, which arevalid for both supercapacitors 90 and fast-charging batteries 100A.E=E _(g) ·w=E _(v) ·d=V·I·t/3600 and P=V·I/w  Equations 1Non-limiting examples for these parameters are presented above.It is noted that, as expressed in Equations 1, the charging/dischargingtime in seconds may be defined as t=E·3600/(V·I).

In order to emulate given supercapacitor 90 by fast-charging battery100A, first their physical dimensions (e.g., sizes or weight) andperformance parameters may be brought into approximate conformation(illustrated in FIG. 2 as configuration 210), depending on the exactperformance requirements. For example, if a given continuous current isrequired, the physical dimensions of fast-charging battery 100A andpossibly the charging/discharging rate may be adjusted (illustrated inFIG. 2 by adjustments 220 and 225, respectively). In another example, ifgiven dimensions are required (e.g., at least of a weight and a sizedimension), the charging/discharging rate may be adjusted (illustratedin FIG. 2 by adjustment 225) and in both cases partial operation range105 is adjusted (illustrated in FIG. 2 by adjustment 230) in order toprovide the required performance.

For example, when given requirement I_(FCB)=I_(SC), the equationE=V·I·t/3600 from Equations 1 may be used to calculate the requiredstored energy E_(FCB) in fast-charging battery 100A and partialoperation range 105 may be determined by the ratio betweenE_(SC)/E_(FCB) to emulate supercapacitor 90 by fast-charging battery100A. In some embodiments, energy storage E_(FCB) may be traded off withrespect to battery dimensions d_(FCB), w_(FCB) to adjust batteryparameter.

In another example, when given requirement w_(FCB)=w_(SC), the equationE=VI/t from Equations 1 may be used to calculate the required currentI_(FCB) and/or charging time t_(FCB) in fast-charging battery 100A andpartial operation range 105 may be determined by the ratio betweenE_(SC)/E_(FCB) to emulate supercapacitor 90 by fast-charging battery100A.

Tables 1 and 2 provide examples of configurations of fast-chargingbattery 100A at two extremes of the range of parameter specifications ofsupercapacitors 90.

TABLE 1 Configuration of fast-charging battery at two extremesupercapacitor specifications, denoted as small and largesupercapacitors 90, under condition of same stored energy. SmallFast-charging Large Fast-charging supercapacitor 90 battery 100 Asupercapacitor 90 battery 100 A Stored energy 0.001 Wh 3.04 WhGravimetric 0.9 Wh/kg 0.9 Wh/kg 6 Wh/kg 11.8 Wh/kg energy densityVolumetric 1.7 Wh/l 3.6 Wh/l 7.7 Wh/l 43.4 Wh/l energy density Power2,400 W/kg 2,500 W/kg 12,000 W/kg 8,500 W/kg Rated voltage 2.7 V 3.35 V2.7 V 3.35 V Maximal 0.7 A 0.8 A 210 A 600 A continuous currentDimensions 12 mm · 8 mm 0.4 mm · 6.25 cm² 138 mm · 60.4 mm 84 mm · 80cm² Volume 0.6 cm³ 0.3 cm3 395 cm³ 70 cm³ Weight 1.1 g 1.1 g 510 g 260 gESR* 700 mOhm 0.29 mOhm Charging time** 1.9 sec 1.2 sec 19.3 sec 5 sec

Table 1 illustrates, in non-limiting examples, the ability to emulatesupercapacitors 90 at two extrema of their range of configurations bycorresponding fast-charging batteries 100A, which achieve similar oreven superior performance.

TABLE 2 Configuration of fast-charging batteries for different types ofrequirements, at two extreme supercapacitor specifications. Smallsupercapacitor Large supercapacitor Requirement: Fixed current Fixedweight Fixed current Fixed weight Charging 50 C.@2% 50 C.@1.7% 50 C.@22%50 C.@3.6% speed and % discharge Stored energy 0.046 Wh 0.056 Wh 13.86Wh 85.46 Wh Gravimetric 50 Wh/kg 50 Wh/kg 170 Wh/kg 170 Wh/kg energydensity Volumetric 200 Wh/l 200 Wh/l 600 Wh/l 600 Wh/l energy densityPower 2,500 W/kg 2,500 W/kg 8,500 W/kg 8,500 W/kg Rated voltage 3.35 V3.35 V 3.35 V 3.35 V Maximal 0.7 A 0.8 A 210 A 1180 A continuous currentDimensions 3.6 mm · 0.55 cm², or 5.4 mm · 0.55 cm², or 84 mm · 160 cm²0.3 mm · 6.25 cm² 0.45 mm · 6.25 cm² Volume 0.2 cm³ 0.3 cm³ 140 cm³Weight 0.9 g 1.1 g 110 g 510 g ESR ~100 mOhm ~100 mOhm ~0.5 mOhm ~0.1mOhm

Table 2 illustrates, in non-limiting examples, the ability to emulatesupercapacitors 90 at two extrema of their range of configurations andaccording to different specifications requirements, by correspondingfast-charging batteries 100A, which achieve similar or even superiorperformance.

Certain embodiments comprise control circuitry 106 of fast-chargingbattery 100A which is configured to provide the respective specifiedcurrent and operate fast-charging battery 100A only within limiteddischarging range 105.

Method 200, as illustrated schematically in FIG. 3, may compriseemulating a supercapacitor with given specifications by a fast-chargingbattery (stage 205) by configuring the fast-charging battery to emulatethe supercapacitor with respect to specified requirements (stage 210),for example by configuring physical dimensions of the battery to providethe required specifications (stage 220), determiningcharging/discharging rate of the battery (stage 225) and/or determiningthe working point and the partial operation range of the battery (stage230). Method 200 may further comprise configuring the control circuitryof the battery to provide the required performance (stage 240).

Method 200 may further comprise selecting the working point within anoptimal operation window (stage 250), possibly selecting the workingpoint as a highly lithiated point within the optimal operation window toreduce relative expansion of the anode material particles duringoperation (stage 255).

Method 200 may further comprise modifying the battery to further enhanceits performance within the operation range (stage 260), e.g., byoptimizing the anode configuration under assumption of operation onlyaround the working point and within the operation range (stage 265)—seee.g., FIG. 4B below.

Modified fast-charging batteries 100A may comprise improved anodes andcells, which enable fast charging rates with enhanced safety due to muchreduced probability of metallization of lithium on the anode, preventingdendrite growth and related risks of fire or explosion. Anodes and/orelectrolytes may have buffering zones for partly reducing and graduallyintroducing lithium ions into the anode for lithiation, to preventlithium ion accumulation at the anode electrolyte interface andconsequent metallization and dendrite growth. Various anode activematerials and combinations, modifications through nanoparticles and arange of coatings which implement the improved anodes are provided. Theelectrolyte in the cell may be chosen to further reduce the accumulationrate of lithium ions at the interface, while maintaining the lithiationin the anode material is the rate limiting factor.

FIG. 4A is a high level schematic illustration of various anodeconfigurations, according to some embodiments of the invention. FIG. 4Aillustrates schematically, in a non-limiting manner, a surface of anode108, which may comprise anode active material particles 110 (e.g.,particles of metalloids such as silicon, germanium and/or tin, and/or ofaluminum), and/or possibly composite core-shell particles 110B, atdifferent sizes (e.g., in the order of magnitude of 100 nm, e.g.,100-500 nm, and/or possible in the order of magnitude of 10 nm or1μ)—for receiving lithiated lithium during charging and releasinglithium ions during discharging. Anodes 108 may further comprisebinder(s) and additive(s) 102 as well as optionally coatings 130 (e.g.,conductive polymers 130A with or without lithium, conductive fibers 130Bsuch as CNTs (carbon nanotubes) or carbon fibers). Active materialparticles 110 may be pre-coated by one or more coatings 120 (e.g., byconductive polymers, lithium polymers, etc.), have borate and/orphosphate salt(s) 128 bond to their surface (possibly forming e.g.,B₂O₃, P₂O₅), bonding molecules 180 (illustrated schematically) which mayinteract with electrolyte 85 (and/or ionic liquid additives thereto)and/or various nanoparticles 112 (e.g., B₄C, WC, VC, TiN) (formingmodified anode active material particles 110A), may be attached theretoin anode preparation processes 111 such as ball milling (see, e.g., U.S.Pat. No. 9,406,927, which is incorporated herein by reference in itsentirety), slurry formation, spreading of the slurry and drying thespread slurry. For example, anode preparation processes 111 may comprisemixing additive(s) 102 such as e.g., binder(s) (e.g., polyvinylidenefluoride, PVDF, styrene butadiene rubber, SBR, or any other binder),plasticizer(s) and/or conductive filler(s) with a solvent such as wateror organic solvent(s) (in which the anode materials have limitedsolubility) to make an anode slurry which is then dried, consolidatedand is positioned in contact with a current collector (e.g., a metal,such as aluminum or copper). Details for some of these possibleconfigurations are disclosed below.

In certain embodiments, modified fast-charging batteries 100A may beoptimized for operation in device 100 by application of modifications260 with respect to fast-charging batteries which are operated overtheir full (nominal) operation range. For example, battery 100A may bemodified (260) to further enhance its performance within the operationrange, e.g., by optimizing the anode configuration under assumption ofoperation only around the working point and within the operation range.For example, the anode material particles may be larger and/or moredensely distributed in anodes 108 configured to operate only around theworking point and within the operation range.

It is explicitly noted that in certain embodiments, cathodes may beprepared according to disclosed embodiments, and the use of the termanode is not limiting the scope of the invention. Any mention of theterm anode may be replaced in some embodiments with the terms electrodeand/or cathode, and corresponding cell elements may be provided incertain embodiments. For example, in cells 100A (of modifiedfast-charging batteries 100A, both designated by numerals 100A withoutlimiting the scope of the invention to either) configured to provideboth fast charging and fast discharging, one or both electrodes 108, 87may be prepared according to embodiments of the disclosed invention.

Anode material particles 110, 110A, 110B, anodes 108 and cells 100A maybe configured according to the disclosed principles to enable highcharging and/or discharging rates (C-rate), ranging from 3-10 C-rate,10-100 C-rate or even above 100 C, e.g., 5 C, 10 C, 15 C, 30 C or more.It is noted that the term C-rate is a measure of the rate of chargingand/or discharging of cell/battery capacity, e.g., with 1 C denotingcharging and/or discharging the cell in an hour, and XC (e.g., 5 C, 10C, 50 C etc.) denoting charging and/or discharging the cell in 1/X of anhour—with respect to a given capacity of the cell.

In certain embodiments, anode 108 may comprise conductive fibers 130Bwhich may extend throughout anode 108 (illustrated, in a non-limitingmanner, only at a section of anode 108) interconnect cores 110 andinterconnected among themselves. Electronic conductivity may be enhancedby any of the following: binder and additives 102, coatings 130A,conductive fibers 130B, nanoparticles 112 and pre-coatings 120, whichmay be in contact with electronic conductive material (e.g., fibers)130.

Lithium ion cell 100A comprises anode(s) 108 (in any of itsconfigurations disclosed herein) made of anode material with compositeanode material such as any of anode material particles 110, 110A, 110B,electrolyte 85 and at least cathode 87 delivering lithium ions duringcharging through cell separator 86 to anode 108. Lithium ions (Li⁺) arelithiated (to Li^(˜0l), indicating substantially non-charged lithium, inlithiation state) when penetrating the anode material, e.g., into anodeactive material cores 110 (possibly of core-shell particles 110B). Anyof the configurations of composite anode material and core-shellparticles 110B presented below may be used in anode 108, as particles110B are illustrated in a generic, non-limiting way. In core-shellparticle configurations 110B, the shell may be at least partly providedby coating(s) 120, and may be configured to provide a gap 140 for anodeactive material 110 to expand 101 upon lithiation. In some embodiments,gap 140 may be implemented by an elastic or plastic filling materialand/or by the flexibility of coating(s) 120 which may extend as anodeactive material cores 110 expand and thereby effective provide room forexpansion 101, indicated in FIG. 4A schematically, in a non-limitingmanner as gap 140. Examples for both types of gaps 140 are providedbelow, and may be combined, e.g., by providing small gap 140 andenabling further place for expansion by the coating flexibility.

Examples for electrolyte 85 may comprise liquid electrolytes such asethylene carbonate, diethyl carbonate, propylene carbonate,fluoroethylene carbonate (FEC), EMC (ethyl methyl carbonate), DMC(dimethyl carbonate), VC (vinylene carbonate) and combinations thereofand/or solid electrolytes such as polymeric electrolytes such aspolyethylene oxide, fluorine-containing polymers and copolymers (e.g.,polytetrafluoroethylene), and combinations thereof. Electrolyte 85 maycomprise lithium electrolyte salt(s) such as LiPF₆, LiBF₄, lithiumbis(oxalato)borate, LiN(CF₃SO₂)₂, LiN(C₂F₅SO₂)₂, LiAsF₆, LiC(CF₃SO₂)₃,LiClO₄, LiTFSI, LiB(C₂O₄)₂, LiBF₂(C₂O₄), tris(trimethylsilyl)phosphite(TMSP) and combinations thereof. Ionic liquid(s) may be added toelectrolyte 85 as disclosed below. Additive(s) (e.g., at few % wt) maycomprise tris(trimethylsilyl)phosphite (TMSP), tris (trimethylsilyl)borate (TMSB), lithium difluoro(oxalato)borate (LiFOB), succinicanhydride, trimethyl phosphate (TMP) and triphenyl phosphate (TFP),fluorinated solvents (methyl nonafluorobutyl ether (MFE), andcombinations thereof. Ionic liquid(s) may be added to electrolyte 85 asdisclosed below.

In certain embodiments, cathode(s) 87 may comprise materials based onlayered, spinel and/or olivine frameworks, and comprise variouscompositions, such as LCO formulations (based on LiCoO₂), NMCformulations (based on lithium nickel-manganese-cobalt), NCAformulations (based on lithium nickel cobalt aluminum oxides), LMOformulations (based on LiMn₂O₄), LMN formulations (based on lithiummanganese-nickel oxides) LFP formulations (based on LiFePO₄), lithiumrich cathodes, and/or combinations thereof. Separator(s) 86 may comprisevarious materials, such as polyethylene (PE), polypropylene (PP) orother appropriate materials. Possible compositions of anode(s) 100 aredisclosed below in detail.

Examples for bonding molecules 180 may comprise e.g., lithium3,5-dicarboxybenzenesulfonate, lithium sulfate, lithium phosphate,lithium phosphate monobasic, lithium trifluoromethanesulfonate, lithium1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfonate,lithium 2,6-dimethylbenzene-1,4-disulfonate, lithium2,6-di-tert-butylbenzene-1,4-disulfonate,3,3-((1,2-dithiane-4,5-diyl)bis(oxy))bis(N-hydroxypropanamide),3,3′-((4-mercapto-1,2-phenylene)bis(oxy))bis(N-hydroxypropanamide),lithium aniline sulfonate (the sulfonate may be in any of para, meta andortho positions) as well as poly(lithium-4-styrenesulfonate), as well asrelated molecules derived therefrom by various substitutions andmodifications, provided as some non-limiting examples.

In FIG. 4A, the different configurations are illustrated schematicallyin different regions of the anode surface, yet embodiments may compriseany combinations of these configurations as well as any extent of anodesurface with any of the disclosed configurations. Anode(s) 108 may thenbe integrated in cells 100A which may be part of lithium ion batteries,together with corresponding cathode(s) 87, electrolyte 85 and separator86, as well as other battery components (e.g., current collectors,electrolyte additives—see below, battery pouch, contacts, and so forth).

In certain embodiments, batteries 100A may be modified to comprisemechanical barriers configured to prevent full expansion of the anodematerial upon lithiation. For example, such mechanical barriers may beconfigured to enable 80% or less of the full expansion of the anodematerial upon lithiation. In certain embodiments, the anode material maycomprise composite anode material particles 110B (see, e.g., FIGS. 4A,4B) having shell structures which are smaller (provide a smallerexpansion volume) than a full expansion volume of cores of the compositeanode material particles. In certain embodiments, cathode(s) 87 ofmodified fast-charging lithium ion battery 100A may be designed to havea smaller capacity than anode(s) 108, as the cathodes are required toprovide a smaller amount of lithium ions when battery 100A operates onlywithin narrow operation range 105.

FIG. 4B is a high level schematic illustration of partial lithiation andmechanical barriers for lithiation of the anode material particles,according to some embodiments of the invention. Fast-charging lithiumion battery 100A may have e.g., Si, Ge and/or Sn-based anode activematerial and be designed to operate at 5 C at least and within operationrange 105 of 5% at most around working point 115 of between 60-80%lithiation of the Si, Ge and/or Sn-based anode active material. FIG. 4Billustrates schematically a small section 108A of anode 108 withcomposite particles 110B, which are depicted in a noon-limiting manneras “yolk and shell” particles comprising anode material particles 110 ascores (“yolks”) internally attached to coating(s) 120 (“shells”) andhaving gap 140 for expansion 101 due to lithiation during formation andcharging.

In prior art use of lithium ion batteries, illustrated schematically bysmall section 108B, anode material particles 110 are being fullylithiated during formation and charging in operation (e.g., 100% SOC,95% or 99% SOC, certain voltage level or minimal voltage changeindication full lithiation etc. as various used indicators of fullcharging). Shells 120A are correspondingly configured (e.g., in aformation process step) to provide gap 140 sufficient to accommodate thefull expansion under lithiation of anode material particles 110.

In contrast, some embodiments may implement partial lithiation to obtainworking point 115 illustrated schematically by small section 108C. Forexample, a formation process may be applied to configure compositeparticles 110B to have partly lithiated anode material particles 110(e.g., with working point 115 being any of 20%, 40%, 60%, 80% orintermediate lithiation states, e.g., in terms of SOC). Operation ofbattery 100A may then be carried out only within operation range 105around working point 115, e.g., ±1% SOC (alternatively, as disclosedherein, ±2%, ±0.5%, ±5%, ±0.1%, ±10% or intermediate operation ranges105 as non-limiting examples). A remaining gap 140A may be configured toserve various purposes such as any of (i) enhancing ionic and/orelectronic conductivity to cores 110 by an appropriate filling material,(ii) maintaining contact of cores 110 with shells 120 (e.g., by elasticfilling material that is compressed during formation), (iii) supportingthe mechanical stability of anode 108 and/or the contact among compositeparticles 110B and so forth.

Alternatively or complementarily, some or all of composite particles110B may be configured with smaller gaps 140B to form mechanicalbarriers (structural limitations) on the possible expansion 101 of cores110. As illustrated schematically in section 108D, full lithiation ofcores 110 may yield an expansion volume 113 (e.g., typically up to 300%in Si as anode material); shells 120B may be configured (e.g., as in agiven structure and/or in a formation step designed for this purpose) tobe smaller than maximum-lithiation expansion volume 113 (e.g., any of20%, 40%, 60%, 80% thereof, or any intermediate value, in terms ofvolume). As illustrated schematically by small section 108E, compositeparticles 110B may comprise anode material particles 110 in shells 120Bwhich have a smaller volume than shells 120, prohibiting full lithiationof cores 110. Accordingly, gaps 140B in non-lithiated state of cores 110may be smaller than prior art gaps 140 designed to accommodate fulllithiation.

Shells 120B may be configured according to working point 115 andoperation range 105, to accommodate just the maximal partial lithiationto which anode 108 and battery 100A are designed, as illustratedschematically by small section 108F.

It is emphasized that gaps 140, 140A, 140B may be implemented by anelastic or plastic filling material in shells 120 and/or implemented bythe flexibility of coating(s) 120 (coating 120 may be configured toextend as anode active material particles 110 expand, to provide roomfor expansion 101).

While contrary to prior art configuration, and counterintuitive in thesense that the potential capacity of the anode material is beingseverely limited already in the design of battery 100A, the inventorshave found that for the supercapacitor emulation applications disclosedherein, designs such as illustrated in section 108F with shells 120Bsmaller than maximum-lithiation expansion volume 113 of anode materialparticles 110 are advantageous in the sense that they enable moreefficient use of space (by avoiding gaps 140A) and result in highervolumetric capacity and higher instantaneous current inputs and outputswhich are important in supercapacitor emulating batteries 100A anddevices 100, as disclosed herein.

FIGS. 5A-5C are high level schematic illustrations relating to theselection of working point 115 and narrow operation range 105, accordingto some embodiments of the invention. FIGS. 5A, 5B illustrateschematically charging and discharging graphs, respectively and FIG. 5Cillustrates an example for an optimal working window for selectingworking point 115, and illustrates an example for considerations forselecting working point 115.

As illustrated schematically in FIGS. 5A-5C, around working point 115and narrow partial operation range 105 may be determined (230) atdifferent locations on either of charging and discharging curves (FIGS.5A and 5B, respectively) according to various considerations. Moreover,modified battery 100A may be re-configured with respect to thedetermined working point 115 and narrow partial operation range 105 toimprove the performance of device 100 even further. In such case,modified battery 100A may no longer be capable of exhibiting fullcharging and discharging ranges as the unmodified lithium ion battery,yet still may be operated within narrow range 105 of its potentialcapacity. For example, anode material particles 110 may be made of Siwhich expands by up to 300% upon lithiation, yet modified battery 100Amay be operated by control unit 106 only in narrow range 105 whichresults in a much narrower range of physical expansion upon lithiation,e.g., of 10% or 20%. As a result, modified battery 100A may be designedto provide less means for coping with expansion 101 of anode materialparticles 110 and as a consequence may be designed to have a largervolumetric capacity than a regular lithium ion battery configured tooperate over the full charging and discharging range.

FIG. 5C illustrates an example for an optimal working window forselecting working point 115, and non-limiting selection considerations,according to some embodiments of the invention. The graph illustrates,in a non-limited manner, an example for the normalized anode DC (directcurrent) resistance performance as function of the state of charge(SOC), and provides the optimal working range for modified battery 100Aas the SOC range with low resistance, in which working point 115 andoperation range 105 may be selected (indicated schematically by sets ofan ornate arrow indicating working point 115 and a double-headed arrowindicating the operation range 105).

FIG. 5C further illustrates schematically anode material particleshaving anode material cores 110 and coating 120 at two ends of theoptimal working window, namely at lower and higher lithiation states atthe left-hand and right-hand sides thereof (with Li^(˜0l) indicating thehigher lithiation state). Expansion 101 is indicated schematically, inan exaggerated manner, for narrow operation range 105 in each case. Inthe lower lithiation state (e.g., 20-30% lithiation) the volume changeof anode material particle 110 with respect to the size of anodematerial particle 110 (its relative expansion) is larger than the volumechange of anode material particle 110 with respect to the size of anodematerial particle 110 (its relative expansion) in the higher lithiationstate (e.g., 70-80% lithiation), because anode material particle 110themselves are larger due to the higher level of lithiation. This effectmay be significant in metalloid-based anode material such as Si, Ge andSn, which expand by 100-500% or more upon lithiation (e.g., Si 400%, Ge270% and Sn 330%). In certain embodiments, working point 115 may beselected at a lithiated state of the anode material in which the anodematerial particles are expanded, so that the additional expansion due tofurther charging is relatively small. In certain embodiments, anodematerial lithiation at working point 115 may be e.g., 50-80%, such as at50%, 60%, 70%, 80% lithiation or at similar values. The inventors havediscovered that as modified battery 100A is operated only over operationrange 105, its design may be optimized for its specific operationspecifications.

In certain embodiments, anode modifications 260 may comprise enhancingionic and/or electronic transport kinetics and conductivity, e.g., byvarious elements disclosed in FIG. 4A such as ionic-conducting coatingsand conductive additives. In addition to the amount of active materialdiscussed above, also anode parameters such as thickness and porositymay be modified to increase the capacity and the conductivity (andthereby the C rate) and enhance the operation of modified battery 100Awithin operation range 105 around working point 115. In certainembodiments, cathode 87 and/or electrolyte 85 may also be modified toenhance operation of modified battery 100A within operation range 105around working point 115.

In certain embodiments, as operation range 105 is restricted withrespect to lithium ion batteries which are used over the whole operationrange, battery 100A may be configured to have smaller cathode(s) 87,e.g., thinner cathode(s) 87, cathode(s) 87 with a smaller area, etc.,having a smaller capacity than anode(s) 108. In certain embodiments,cathode(s) 87 may have a charge capacity that is smaller than the chargecapacity of anode(s) 108 by e.g., 10%, 20%, 30% or even 40%. Forexample, cathode(s) 87 may have a capacity of 90%, 80%, 70%, 60%,respectively, of the capacity of anode(s) 108. These differences may bewith respect to pristine cathodes and anodes, and/or with respect tocathodes and anodes in operation. It is noted that as some of thecathode lithium is absorbed in the solid electrolyte interface (SEI)during the formation process, a required operational cathode-anode loadratio may be implemented as a larger cathode-anode load ratio of thepristine electrodes. As operation range 105 is set to be smaller, thecathode-anode load ratio may also be smaller, requiring smallercathodes.

Advantageously, disclosed fast-charging battery 100A and/or devices 100do not only emulate supercapacitors to provide comparable or betterperformance, but are also superior to equivalent supercapacitors inhaving lower self-discharge rates, higher working potentials, shortercharging times and higher energy densities than comparablesupercapacitors.

For example, fast-charging batteries 100A typically provide an averageoutput voltage level above 3V (e.g., 3.35V averaged from 4.3V to 2V)while supercapacitors are typically specified at 2.7V output voltage oreven less, which moreover decays with self-discharge of thesupercapacitor. Fast-charging batteries 100A and/or devices 100therefore provide a wider usable voltage range that broadens theoperating margin for designers using them, with respect to usingequivalent supercapacitors.

Moreover, operating fast-charging batteries 100A and/or devices 100 maybe configured to provide a very stable output voltage which isbeneficial in many product designs. Not only that fast-chargingbatteries 100A provide most of their energy capacity at a stable voltagelevel (e.g., 3.35V), but they regulated operation within narrowoperation range 105 around working point 115 enhances the constancy ofthe output (and/or input) operation voltage significantly. The verystable output voltage delivered by disclosed fast-charging batteries100A and/or devices 100 stands in stark contrast to equivalentsupercapacitors which typically produce an output voltage that islinearly proportional to their charge (e.g., a supercapacitor fullycharged to 3.3V delivers 3.3V at 100% charge but only 1.65V at 50%charge, which is below the level required by many processors and otherdevices).

It is also noted that the low levels of self-discharge of fast-chargingbatteries 100A and/or devices 100 with respect to equivalentsupercapacitors is advantageous in avoiding the over-design of powersources in systems using supercapacitors, required to compensate forsupercapacitors' high losses. For example, in certain embodiments,fast-charging batteries 100A and/or devices 100 may be configured tooperate at a voltage level of at least 3V, and have a leakage currentsmaller than 0.1% of a respective maximal continuous current.

In the above description, an embodiment is an example or implementationof the invention. The various appearances of “one embodiment”, “anembodiment”, “certain embodiments” or “some embodiments” do notnecessarily all refer to the same embodiments. Although various featuresof the invention may be described in the context of a single embodiment,the features may also be provided separately or in any suitablecombination. Conversely, although the invention may be described hereinin the context of separate embodiments for clarity, the invention mayalso be implemented in a single embodiment. Certain embodiments of theinvention may include features from different embodiments disclosedabove, and certain embodiments may incorporate elements from otherembodiments disclosed above. The disclosure of elements of the inventionin the context of a specific embodiment is not to be taken as limitingtheir use in the specific embodiment alone. Furthermore, it is to beunderstood that the invention can be carried out or practiced in variousways and that the invention can be implemented in certain embodimentsother than the ones outlined in the description above.

The invention is not limited to those diagrams or to the correspondingdescriptions. For example, flow need not move through each illustratedbox or state, or in exactly the same order as illustrated and described.Meanings of technical and scientific terms used herein are to becommonly understood as by one of ordinary skill in the art to which theinvention belongs, unless otherwise defined. While the invention hasbeen described with respect to a limited number of embodiments, theseshould not be construed as limitations on the scope of the invention,but rather as exemplifications of some of the preferred embodiments.Other possible variations, modifications, and applications are alsowithin the scope of the invention. Accordingly, the scope of theinvention should not be limited by what has thus far been described, butby the appended claims and their legal equivalents.

The invention claimed is:
 1. A device comprising control circuitry and amodified fast-charging lithium ion battery having Si, Ge and/or Sn-basedanode active material and designed to operate at 5C at least and withinan operation range of 5% at most around a working point of between60-80% lithiation of the Si, Ge and/or Sn-based anode active material,wherein the control circuitry is configured to maintain a state ofcharge (SOC) of the battery within the operation range around theworking point, wherein the anode active material is configured to enableoperation of the modified fast-charging lithium ion battery only aroundthe working point and within the operation range, wherein an anode ofthe modified fast-charging lithium ion battery comprises mechanicalbarriers configured to prevent full expansion of the anode material uponlithiation and wherein the anode material comprises composite anodematerial particles having shell structures which are smaller than a fullexpansion volume of cores of the composite anode material particles. 2.The device of claim 1, wherein the mechanical barriers are configured toenable 80% or less of the full expansion of the anode material uponlithiation.
 3. The device of claim 1, wherein a cathode of the modifiedfast-charging lithium ion battery has a capacity of 80% or less than theanode.
 4. The device of claim 1, configured to operate at a voltagelevel of at least 3V, and have a leakage current smaller than 0.1% of arespective maximal continuous current.
 5. A fast-charging lithium ionbattery having Si, Ge and/or Sn-based anode active material andoperating at least at 5 C charging rate, only within an operation rangeof 5% at most around a working point of between 60-80% lithiation of theSi, Ge and/or Sn-based anode active material, wherein the battery ismodified to enable operation thereof only around the working point andwithin the operation range, wherein an anode of the battery comprisesmechanical barriers configured to prevent full expansion of the anodematerial upon lithiation, wherein the mechanical barriers are configuredto enable 80% or less of the full expansion of the anode material uponlithiation, and wherein the anode material comprises composite anodematerial particles having shell structures which are smaller than a fullexpansion volume of cores of the composite anode material particles. 6.The fast-charging lithium ion battery of claim 5, wherein a cathodethereof has a capacity of 80% or less than an anode thereof.